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A presente pesquisa tem como finalidade o estudo de ensaio de aderência para revestimentos de argamassa, a partir de esforços de cisalhamentos. A ABNT NBR 13528:2010 trata do ensaio de aderência de revestimento, determinada por meio da aplicação de uma carga constante, normal, aplicada sobre um suporte metálico ligado diretamente a um corpo-de-prova do revestimento a ser ensaiado. Nessa pesquisa procurou-se verificar, em laboratório, a determinação da resistência de aderência ao cisalhamento como mais um parâmetro na avaliação dos revestimentos de argamassa. Esse estudo foi realizado através do ensaio de arrancamento oblíquo ao revestimento a ser analisado. A mesma norma recomenda que, para delimitação da superfície do corpo-de-prova, esses deverão ser de forma circular de 50 mm de diâmetro. No entanto, nesse trabalho foram utilizados corposde- prova de seção quadrada de 100 mm de lado com a finalidade de adaptar-se à forma e ao tipo de execução dos ensaios a serem realizados na pesquisa. Para realização da pesquisa foram confeccionados painéis de blocos cerâmicos revestidos com argamassa sobre os quais foram ensaiados corpos-de-prova sob os ângulos de 0, 45 e 90. Para tornar possível a realização dos ensaios sob os ângulos de 45 e 0 foi necessário elaborar dispositivos adaptadores para execução dos respectivos ensaios. O objetivo desse trabalho consistiu em determinar a resistência de aderência ao cisalhamento a partir da aplicação de uma carga de arrancamento aplicada obliquamente ao revestimento. Através de uma Análise de variância, verificou-se que os resultados obtidos apontam uma relação entre a carga de arrancamento oblíqua (45) e a resistência de aderência ao cisalhamento (0), objetivo dessa pesquisa / This research studies aims the determination of bond of rendering mortar, through shear efforts. The ABNT NBR 13528:2010 prescribes the test method of bond strength of mortar rendering, determined a constant load applied on a normal metallic device, connected directly to a specimen rendering mortar to be tested. This survey sought to verify, in the laboratory, the determination of resistance to shear adhesion as another parameter in the evaluation of rendering mortar. This study was carried out by testing pullout oblique to the rendering to be parsed. The same standard recommends that delimitation of the body surface-specimens these should be circular 50 mm in diameter. However, in this work were used specimens of squared form whose sides measure 100 mm having both surfaces in order to adapt the form and type of carrying out the tests to be carried out in the search. For the research achievement were made of ceramic bricks panels which were tested specimens under the angles from 0, 45 and 90. To make it possible to carry out the tests under the angles of 45 and 0 required adapter devices to run their tests. The goal of this work was to determine the resistance to shear adhesion from applying a load of pullout applied obliquely to finish. Through an analysis of variance, the results suggest a relationship between the workload pullout oblique (45) and the resistance to shear adhesion (0), goal of this research

The viscoelastic response of polymer-based composite laminates, which may take years to develop in service, must be anticipated and accommodated at the design stage. Accelerated testing is therefore required to allow long-term compliance predictions for composite laminates of arbitrary layup, based solely upon short-term tests. In this study, an accelerated viscoelastic characterization scheme is applied to T300/5208 graphiteepoxy laminates. The viscoelastic response of unidirectional specimens is modeled using the theory developed by Schapery. The transient component of the viscoelastic creep compliance is assumed to follow a power law approximation. A recursive relationship is developed, based upon the Schapery single-integral equation, which allows approximation of a continuous time-varying uniaxial load using discrete steps in stress. The viscoelastic response of T300/5208 graphite-epoxy at 149C to transverse normal and shear stresses is determined using 90-deg and 10-deg off-axis tensile specimens, respectively. parameters In each case the seven viscoelastic material required in the analysis are determined experimentally, using a short-term creep/creep recovery testing cycle. A sensitivity analysis is used to select the appropriate short-term test cycle. It is shown that an accurate measure of the power law exponent is crucial for accurate long-term predictions, and that the calculated value of the power law exponent is very sensitive to slight experimental error in recovery data. Based upon this analysis, a 480/120 minute creep/creep recovery test cycle is selected, and the power law exponent is calculated using creep data. A short-term test cycle selection procedure is proposed, which should provide useful guidelines when other viscoelastic materials are being evaluated. Results from the short-term tests on unidirectional specimens are combined using classical lamination theory to provide long-term predictions for symmetric composite laminates. Experimental measurement of the long-term creep compliance at 149C of two distinct T300/5208 laminates is obtained. A reasonable comparison between theory and experiment is observed at time up to 10 5 minutes. Discrepancies which do exist are believed to be due to an insufficient modeling of biaxial stress interactions, to the accumulation of damage in the form of matrix cracks or voids, and/or to interlaminar shear deformations which may occur due to viscoelastic effects or damage accumulation. / Doctor of Philosophy

Made available in DSpace on 2017-06-01T17:57:30Z (GMT). No. of bitstreams: 1 dissertacao_carlos_roberto.pdf: 2598523 bytes, checksum: 872e5c7267f4bd04a6a400771fd9f157 (MD5) Previous issue date: 2010-10-21 / This research studies aims the determination of bond of rendering mortar, through shear efforts. The ABNT NBR 13528:2010 prescribes the test method of bond strength of mortar rendering, determined a constant load applied on a normal metallic device, connected directly to a specimen rendering mortar to be tested. This survey sought to verify, in the laboratory, the determination of resistance to shear adhesion as another parameter in the evaluation of rendering mortar. This study was carried out by testing pullout oblique to the rendering to be parsed. The same standard recommends that delimitation of the body surface-specimens these should be circular 50 mm in diameter. However, in this work were used specimens of squared form whose sides measure 100 mm having both surfaces in order to adapt the form and type of carrying out the tests to be carried out in the search. For the research achievement were made of ceramic bricks panels which were tested specimens under the angles from 0°, 45° and 90°. To make it possible to carry out the tests under the angles of 45° and 0° required adapter devices to run their tests. The goal of this work was to determine the resistance to shear adhesion from applying a load of pullout applied obliquely to finish. Through an analysis of variance, the results suggest a relationship between the workload pullout oblique (45°) and the resistance to shear adhesion (0°), goal of this research / A presente pesquisa tem como finalidade o estudo de ensaio de aderência para revestimentos de argamassa, a partir de esforços de cisalhamentos. A ABNT NBR 13528:2010 trata do ensaio de aderência de revestimento, determinada por meio da aplicação de uma carga constante, normal, aplicada sobre um suporte metálico ligado diretamente a um corpo-de-prova do revestimento a ser ensaiado. Nessa pesquisa procurou-se verificar, em laboratório, a determinação da resistência de aderência ao cisalhamento como mais um parâmetro na avaliação dos revestimentos de argamassa. Esse estudo foi realizado através do ensaio de arrancamento oblíquo ao revestimento a ser analisado. A mesma norma recomenda que, para delimitação da superfície do corpo-de-prova, esses deverão ser de forma circular de 50 mm de diâmetro. No entanto, nesse trabalho foram utilizados corposde- prova de seção quadrada de 100 mm de lado com a finalidade de adaptar-se à forma e ao tipo de execução dos ensaios a serem realizados na pesquisa. Para realização da pesquisa foram confeccionados painéis de blocos cerâmicos revestidos com argamassa sobre os quais foram ensaiados corpos-de-prova sob os ângulos de 0°, 45° e 90°. Para tornar possível a realização dos ensaios sob os ângulos de 45° e 0° foi necessário elaborar dispositivos adaptadores para execução dos respectivos ensaios. O objetivo desse trabalho consistiu em determinar a resistência de aderência ao cisalhamento a partir da aplicação de uma carga de arrancamento aplicada obliquamente ao revestimento. Através de uma Análise de variância, verificou-se que os resultados obtidos apontam uma relação entre a carga de arrancamento oblíqua (45°) e a resistência de aderência ao cisalhamento (0°), objetivo dessa pesquisa

The purpose of this study is to determine whether chlorinated polymers such as polyvinylchloride (PVC) and polyvinylidenechloride (PVDC) degrade in a fretting interface. Polymer coated 52100 steel balls are fretted against a polished 1045 steel plate for 30 minutes in air and nitrogen at 25-30 percent and greater than 95 percent relative humidity. ESCA analysis is used to determine interface chemistry and help conclude that the color formation observed in the polymer coating is due to polymer degradation. Additional tests of thermally stabilized PVC on a steel plate supported this theory and aided in understanding the polymers performance in the interface. Experiments with the “pure” PVC on a glass plate showed that iron at the interface can initiate and catalyzes the polymer degradation. The effects of the different atmospheres, as well as the effect of humidity is also presented. / M.S.

Approximately five percent of the volume of red oak lumber which is harvested for use in the furniture and flooring industries in the United States is unusable due to surface checking. This thesis investigated the possibility of reducing surface checking by controlling the lumber boundary conditions. Boundary control was accomplished by applying a coating directly to the lumber surfaces.· The investigation included development of a computerized simulation to model drying behavior, testing a number of coatings to determine moisture loss resistance and evaluation of a coating using full-sized lumber tests. The results indicate a coating can be a viable method of reducing surface checking under severe drying conditions. / M.S.

A fundamental study was conducted to investigate the ability of thin polymeric coatings to prevent metallic contact and fretting corrosion in steel-on-steel systems. Ten polymer types were chosen for study: polymethylmethacrylate (PMMA), polytetrafluoroethylene (PTFE), polyimide (PI), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), low-density polyethylene (LOPE), high-density polyethylene (HDPE), polysulfone (PSO) and polystyrene (PS). These polymers were applied as thin films to a steel disk which was in turn fretted by a normally-loaded steel sphere. The experimental investigation consisted of two phases. In the first phase, the lives of the ten polymer types were evaluated over a range of normal loads from 11.1 to 44.5 N. In the second phase, optical and electron microscopy were used to document the fretting process at the sphere-film interface as a function of time. / Master of Science

Thin polymeric coatings have been applied to metal surfaces to prevent and/or prolong the onset of fretting corrosion, but the properties that make a polymeric coating effective and the means by which a coating fails are unknown. The purpose of this study was to determine the effect of molecular weight, casting solvent, and amplitude of motion on the life of thin (25 ~m nominal) polystyrene coatings. Narrow molecular weight distribution polystyrene coatings ranging from <Mw>=19,400 to <Mw>=1,460,000 were applied to UNS G10450 steel disks with toluene and MEK as casting solvents. The coatings were fretted against UNS G52100 steel balls at 20 Hz under 22.3 N normal load. Amplitudes of motion ranged from 100 ~m to 500 ~m. Coating life and friction force were measured. Coatings of <Mw>=207,700 showed maximum life at all amplitudes. Friction remained constant for all tests, and increasing amplitude decreased life. Toluene-cast coatings had slightly shorter lives and more coating racks than MEK-cast coatings. Toluene-cast coatings below <Mw>=53,700 cracked severely during solvent removal and were not tested. / Master of Science

The purpose of this study was to investigate the effects and interactions of lead, frequency, amplitude of slip, humidity, and film thickness of polyvinyl chloride on fretting corrosion. In particular, this study describes the effects of these parameters on the polymer film life and also on the wear of the metal surfaces after metallic contact had occurred. The two levels that were used for each parameter are: load, 15.6 and 31.1 N (3.5 and 7.0 lb); amplitude of slip, 165 and 330 μm (6.5 and 13 mils); frequency of slip, 20 and 40 Hz; humidity of air, 16.6 percent, and 58.4 percent relative humidity; and PVC film thickness, 20 and 37 μm (0.8 and 1.45 mils). The 52100 steel balls were loaded against a 1045 steel disk that was coated with PVC. This configuration was then subjected to a two-level, five-factor experiment comprised of the above levels of conditions. / M.S.